Certain industrial machinery requires high viscosity lubricating compositions, for example gears, bearings, couplings, and pumps. There are several known high viscosity lubricating compositions for such machinery.
U.S. Pat. No. 7,790,660 to Carey et al. discloses polyalkylene glycol (PAG) lubricants including rust inhibiting compositions used in worm drive gear boxes. The rust inhibitors consist of an N-acyl sarcosine and an imidazole while the antioxidant consists of an alkylated diphenyl amine and a hindered phenol. These lubricants deliver lower operating temperature in worm drive gear boxes.
U.S. Pat. No. 5,602,086 to Shim et al. discloses a lubricating composition of enhanced thermal and oxidation stability. The lubricating composition is produced from a blend of components including an API Group V base stock, such as alkylated naphthalene having a kinematic viscosity of 13 cSt at 100° C.; and a polyalphaolefin (PAO) base stock having a kinematic viscosity of 300 cSt or less at 100° C. An example composition includes 10 weight percent (wt %) alkylated naphthalene having a kinematic viscosity of 5 cSt at 100° C.; 87.62 wt % polyalphaolefin (PAO) base stock having a kinematic viscosity of 100 cSt at 100° C.; and 2.38 wt % additives.
US 2008/0020954 to Carey et at discloses a lubricating composition for worm drive gears comprising a blend of polyalphaolefin base stocks having viscosity differences of at least 200 cSt. The polyalphaolefin base stocks may be reaction products of metallocene catalysts. An example lubricating composition includes at least 19.7 wt % of a first polyalphaolefin base stock having a kinematic viscosity of at least 300 cSt at 100° C.; at least 29.0 wt % of a second polyalphaolefin base stock having a kinematic viscosity less than 60 cSt at 100° C.; and not greater than 13.3 wt % of an API Group V base stock, for example alkylnaphthalene or alkylbenzene.
US 2007/0000807 to Wu et al. discloses a lubricating composition for worm drive gears produced from a blend of an API Group V base stock, for example alkylnapthalene or alkylbenzene; and a polyalphaolefin base stock. An example composition includes 20.0 wt % of the API Group V base stock, and 78.25 wt % of the polyalphaolefin base stock.
US 2009/0036725 to Wu et al. discloses liquid a polyalphaolefin and process for producing the polyalphaolefin. The liquid polyalphaolefins (PAOs) are produced in the presence of a meso-metallocene catalyst with a non-coordinating anion activator and, optionally, a co-activator. The PAOs can be combined with one or more other base stocks, including Group I to Group VI base stocks with viscosity range from 1.5 to 100 cSt at 100° C. to formulate suitable viscosity grades of finished oils.
The operating temperature and efficiency of any lubricating composition is especially important to the designers, builders, and user of certain industrial machinery, such as worm drive gear boxes for material handling systems. A higher percentage efficiency rating for a lubricating composition results in more power being transmitted through the machinery and less power being wasted to friction or heat. For example, a 3% efficiency gain in a baggage handling system with 300 worm drive gear boxes is worth about $15,000 per year in electricity savings. A decrease of 10° C. of operating temperature can double the life of seals used in the machinery, and decrease overall costs of operation and ownership. Thus, designers, builders, and users of such machinery are constantly striving to obtain more efficient lubricants.